Hot-air furnace



M e e h s W e e h S 2 N O Nw A M 0 N R in M H R n d 0 M 0 w No. 605,517. Patented June 14,1898.

RM (K (No Model.) 2 Sheets-Sheet 2.

R. & E. ROBINSON.

HQT AIR FURNACE.

No. 606,517. Patented June 14,1898

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ROBERT ROBINSON AND EDWARD I-I. ROBINSON, OF CHICAGO, ILLINOIS.

HOT-AIR FURNACE.

srncrmoarron forming part of Letters 'Patent No. 605,517, dated June 14, 1898.-

Application filed March 22, 1897.-

To all whom it may coltcern:

Be it known that we, ROBERT ROBINSON and EDWARD II. ROBINSON, of Chicago, Illinois, have invented certain new and useful Improvements in Hot-Air Furnaces, of which the following is a specification.

This invention relates to that class of airheating furnaces in which a vertically-arranged series of heating-tubes are employed,

bility to choking of such passages from soot.

The present construction further provides a furnace having a high efficiency and capable of heating a large volume of air quickly while affording complete combustion. To carry out may freely pass.

these objects,the furnace is provided with two series of tubes arranged concentrically to the vertical axis of the fire-pot, with a front opening opposite the fuel-door and a rearopening through which the products of combustion The tubes are so arranged with reference to the casing or shell as to provide annular passages,which return the products of combustion toward the front of the furnace, such annular passages being closed off from the front opening by curved partiabove the fire to the rear of the furnace, the

single smoke flue or duct being formed with or constituting a part of the dome. This flue passing across the axis of the fire-chamber is exposed to intense heat on its lower side while the heated products of combustion pass through it, thus making said flue an efficient auxiliary to the heating of the dome and ex.- posing an additional and extended heatingsurface to theair to be warmed. By providing an openingin the front portion of this duct covered with a movable damper or valve a direct draft may be secured or the products of combustion may be caused to make the circuit of the ai r-tubcs.

an no. 628,571. (No model.)

The inventionis illustrated in the accompanying drawings, in which- "Figure 1 is a central sectional elevation through the heatingchamber and casing. Fig. 2 is a plan view with the top of the casing removed. Fig. 3 is sectional View at right angles to that shown in Fig. 1. Fig. 4 is a transverse sectional planview through the tubes.

In the drawings let 5 6 represent the tubes, which are arranged in two series concentrically to the axis of the fire-chamber 7. The

tubes are separated at the rear to provide the lateral passage 8, and they are also separated at the front to afford the fuel-opening 9. The lower ends of the tubes are set into the hanged ring 10 and their upper ends in theflange of the dome 11. The casing 12 surrounds the sets of tubes and affords annular passages 13 for the products of combustion, which pass through the lateral opening 8 and, dividing, return to the front of the furnace. The passages 13 are closed off from the fuel-opening 9 by means of the curved vertically-arranged partition-plates 14, which constitute particircular fines 15, to the upper ends of which are joined the branch pipes 10, which may be formed integrally with the dome and united with or lead into the horizontal flue 17. The lower wall of this flue 17 is preferably separately formed and consists of a semicylindrical casting, (marked 18,) which maybe flanged and bolted or riveted to the dome-section, this being simply for convenience in casting. This flue 17 may lead direct to the chimney. In the lower wall of this passage and preferably at about the junction of the branches 16 with the main flue 17 openings 19 are protraverse it is obvious that the products of combustion act to highly heat the air passing ICO upwardly through the flues, the latter being arranged in a usual manner, so that their sides make contact, thus causing the heat to pass to the rear and thence return on the outside of the series of flues and the smoke and heated gases finally escaping to the chimney through the flue 17 and imparting heat to the dome, with which the air is also in contact. The lower portion 18 of this flue l7 traverses the furnace horizontally immediately above the fire-chamber, and consequently is very highly heated, so that the dome to which it is joined also receives a high degree of heat by radiation.

The construction above described is particularly intended and adapted for burning soft coal. IIeretofore furnaces which have been constructed to burn soft coal have had practically direct drafts, so that a great deal of heat was lost by passing directly to the chimney. This is coneededly a very wasteful method and has long since been abandoned in furnaces intended to burn hard coal. The difficulty to be overcome in the way of applying the same principle to a soft-coalburning furnace has been to prevent clogging by soot. IV e avoid this difficulty in the present construction by the large passages 13, which are readily accessible for cleaning through the clean-out doors 24, and through these doors all portions of the passages can easily be reached with a brush. In order to clean the horizontal flue 17 ,we provide therein flue-stops 25. As this furnace may also be used for burning wood, it is adapted to this use by the provisions of the double doors 26 27, and when the latter is opened access may readily be had to the flue-stop 25 and through the opening covered thereby to the flue 17.

By the construction above described. the furnace is adapted for burning soft coal or wood with the same relative economy as is attained in burning hard coal, the products of combustion being caused to circulate about the air-tubes as effectively as in a hard-coal furnace.

WVithout limiting our invention to the precise structural details, we claim- 1. In a hot-air furnace the combination with a suitable casing, of a series of tubes constitutextending thence rearwardly across the firechamber at the top thereof, substantially as described.

2. In a hot-air furnace the combination with air-tubes arranged in series at the sides of the furnace and the individual tubes being in contact with each other concentrically to the firepot, a shell forming with said tubes annular passages and said tubes being separated to provide a rear exit for the products of combustion communicating with said passages, partitions closing the front ends of said annular passages and ducts leading from the front and upper ends of said passages to a central smoke-flue and said flue extending above the fire-chamber and delivering out of the furnace toward the rear thereof, substantially as described.

3. In a furnace of the class described, the combination of a suitable shell or casing, a series of air-tubes separated at the rear to provide a passage for the products of combustion and from the casing to provide annular lateral passages, a central dome and a central flue having its upper portion formed integral with said dome on the lower side thereof and provided with a separable lower portion, and external tubular branches connecting said central flue with the front ends of the lateral passages, substantially as described. 4

4. The combination with a furnace'dome having a portion of a smoke-flue formed integrally with the lower side thereof, an attachable portion completing said flue, external branches also formed integrally with the dome and a clean-out opening at the junction of said branches and in line with the flue, substantially as described.

5. In a furnace of the character described, the combination, with a suitable shell or casing and a series of air-tubes therein separated at the rear and forming annular passages Within the casing closed at their front ends, of a dome having a smoke-flue on its under side connected at its front end with said annular passages and having an opening in its lower Wall near the front end communicating directly with the fire chamber, and a damper controlling said opening, substantiallyv as described.

- ROBERT ROBINSON.

EDWARD I-I. ROBINSON. IVit-nesses:

FREDERICK O. GooDWIN,

LoUIs T. MANN. 

